The invention pertains to an aqueous-based slurry and a method of emplacing a resin consolidated pack of particulate material between the casing of a well and an unconsolidated formation. The invention also pertains to novel substituted aromatic amines which are useful, for example, as epoxy crosslinking agents in said slurry.
Production of detritus in wells which penetrate unconsolidated, i.e., incompetent, subterranean formations, is an ever present problem, particularly in the petroleum industry. A good discussion of the problem, and of the various techniques used to minimize concurrent production of such detritus can be found in an eight part series by George O. Suman, Jr., appearing in World Oil from November, 1974, through June, 1975. The series was published in 1975 as a reprint by Gulf Publishing Co., under the title "World Oil's Sand Control Handbook," the teachings of which are expressly incorporated herein. Three commonly used methods are (1) gravel packing, (2) plastic in situ consolidation, and (3) consolidated packing with a particulate material, often called consolidated gravel packing especially where the particulate material is sand. The latter technique is discussed in Part 7 of said Handbook, and it is this latter technique to which the present invention pertains.
In the early consolidated gravel packing art, typified by Henderson et al., U.S. Pat. No. 2,823,753, it was taught to precoat a particulate with a resin, suspend the coated particulate in a suitable carrier, and inject the suspension into the borehole.
Precoated particulates have had several drawbacks to overcome. Some precoated particulates were not sufficiently stable to be stored and transported without agglomeration. Others which could be handled without an objectionable degree of agglomeration suffered from an inability to form packs having high compressive strengths in low temperature wells, while simultaneously maintaining adequate permeability. Consequently, efforts were generally concentrated on developing high particulate concentration oil based slurries which could be prepared without precoating the particulate prior to admixture with the carrier, and in maximizing the strength and permeability parameters of such systems.
Oil based systems also suffered from numerous inherent disadvantages. In offshore operations, any unused oil carried slurry had to be transported back to shore, and even on land, disposal in an ecologically acceptable manner presented a problem. This, and high inventory costs adversely affected the economics of the treatment, particularly in periods of tight supply. Safety risks were somewhat greater with large quantities of combustible material at the well site and quality control was a problem. Some sources of bright stock oil have such high levels of cationic contaminants that poorly consolidated packs can result, even after attempts to neutralize the effect of such contaminants by best available technology, such as by implementation of the teachings at column 4, line 60 et seq. of Copeland, U.S. Pat. No. 3,867,986. Numerous handling problems were also associated with the oil-based systems (due to this high viscosity and friction loss) which made well operators reluctant to use oil carried systems in gas wells because of concern of possible formation damage by injection of heavy oils and/or excessive pressures at the well head. As a result, the fracturing technique taught by Gurley et al. in U.S. Pat. No. 3,854,533 could not always be implemented safely. Finally, the sensitivity of oil-carried systems to water based fluids required careful handling prior to injection, and the use of oil as a displacing fluid or the use of a wiper plug to separate the slurry from a water-based displacement fluid.
A substantial advancement in the art was made by Copeland et al., in U.S. Pat. No. 4,074,760 and U.S. Pat. No. 4,101,474, in which they described an aqueous based slurry containing an aqueous carrier fluid, an epoxy resin, a curing agent for the resin, a solvent for said resin and curing agent, a finely divided particulate material, a particular quaternary ammonium halide, and a coupling agent to promote bonding of the resin to the particulate.
Carpenter et al., in U.S. Pat. No. 4,081,030 described a further improvement over Copeland et al. Carpenter et al. included certain chelating agents in the carrier fluid which made it less sensitive to polyvalent metal cations which are normally encountered under conditions of use. Such cations can adversely affect the performance of the gravel pack.
The disclosures of the Copeland et al., and Carpenter et al. patents are incorporated herewith by reference.